Refactor test files for improved readability and consistency

- Removed unnecessary blank lines and adjusted formatting in test files.
- Ensured consistent use of commas in function calls and assertions across various test cases.
- Updated import statements for better organization and clarity.
- Enhanced mock setups in tests for better isolation and reliability.
- Improved assertions to follow a consistent style for better readability.

app/services/vlc_player.py

@@ -6,7 +6,6 @@ from collections.abc import Callable
 from pathlib import Path
 from typing import Any
 
-from sqlmodel import select
 from sqlmodel.ext.asyncio.session import AsyncSession
 
 from app.core.logging import get_logger